use std::{
	ops::{Deref, DerefMut},
	ptr,
};

use super::{Audio, Decoder, Subtitle, Video};
use crate::{
	codec::{Context, Profile},
	ffi::*,
	media, packet, Error, Frame, Rational,
};

pub struct Opened(pub Decoder);

impl Opened {
	pub fn video(self) -> Result<Video, Error> {
		if self.medium() == media::Type::Video {
			Ok(Video(self))
		}
		else {
			Err(Error::InvalidData)
		}
	}

	pub fn audio(self) -> Result<Audio, Error> {
		if self.medium() == media::Type::Audio {
			Ok(Audio(self))
		}
		else {
			Err(Error::InvalidData)
		}
	}

	pub fn subtitle(self) -> Result<Subtitle, Error> {
		if self.medium() == media::Type::Subtitle {
			Ok(Subtitle(self))
		}
		else {
			Err(Error::InvalidData)
		}
	}

	pub fn send_packet<P: packet::Ref>(&mut self, packet: &P) -> Result<(), Error> {
		unsafe {
			match avcodec_send_packet(self.as_mut_ptr(), packet.as_ptr()) {
				e if e < 0 => Err(Error::from(e)),
				_ => Ok(()),
			}
		}
	}

	/// Sends a NULL packet to the decoder to signal end of stream and enter
	/// draining mode.
	pub fn send_eof(&mut self) -> Result<(), Error> {
		unsafe {
			match avcodec_send_packet(self.as_mut_ptr(), ptr::null()) {
				e if e < 0 => Err(Error::from(e)),
				_ => Ok(()),
			}
		}
	}

	pub fn receive_frame(&mut self, frame: &mut Frame) -> Result<(), Error> {
		unsafe {
			match avcodec_receive_frame(self.as_mut_ptr(), frame.as_mut_ptr()) {
				e if e < 0 => Err(Error::from(e)),
				_ => Ok(()),
			}
		}
	}

	pub fn bit_rate(&self) -> usize {
		unsafe { (*self.as_ptr()).bit_rate as usize }
	}

	pub fn delay(&self) -> usize {
		unsafe { (*self.as_ptr()).delay as usize }
	}

	pub fn profile(&self) -> Profile {
		unsafe { Profile::from((self.id(), (*self.as_ptr()).profile)) }
	}

	pub fn frame_rate(&self) -> Option<Rational> {
		unsafe {
			let value = (*self.as_ptr()).framerate;

			if value == (AVRational { num: 0, den: 1 }) {
				None
			}
			else {
				Some(Rational::from(value))
			}
		}
	}

	pub fn flush(&mut self) {
		unsafe {
			avcodec_flush_buffers(self.as_mut_ptr());
		}
	}
}

impl Drop for Opened {
	fn drop(&mut self) {
		unsafe {
			avcodec_close(self.as_mut_ptr());
		}
	}
}

impl Deref for Opened {
	type Target = Decoder;

	fn deref(&self) -> &<Self as Deref>::Target {
		&self.0
	}
}

impl DerefMut for Opened {
	fn deref_mut(&mut self) -> &mut <Self as Deref>::Target {
		&mut self.0
	}
}

impl AsRef<Context> for Opened {
	fn as_ref(&self) -> &Context {
		self
	}
}

impl AsMut<Context> for Opened {
	fn as_mut(&mut self) -> &mut Context {
		&mut self.0
	}
}
